2. . .
Displacement compressor , screw compressor , rotary compressor , twin cylinder compressor - - , in either case , suction strainer -, cylinder block , metallic fragments (), delivery valve , suction valve , valve plate (), upper side , under side , delivery port , connecting rod , lined with white metal , gland box , metal bushes , cast iron housing , end thrust , special hardened steel , oil pump spirals , oil rings , the shaft rotates - , is shown in Fig , n no account , ordinary engine , to cause trouble ( ), is driven by , is coupled to the electric motor , flexible coupling , is provided - , direction of rotation , working parts , to cause damage
3. .
may , .
1. The crankshaft may be carried on main bearings.
2. A pure mineral oil may be used in the crankcase.
3. Thrust bushes may be made of special hardened steel.
4. The compressor may be driven by an electric motor.
5. Delivery valves may be mounted on the valve plate.
6. Serious damage may be caused by the lubrication stop.
for what purpose
1. For what purpose are thrust bushes placed at the end of the crankshaft?
2. For what purpose is a flexible coupling provided to connect the motor to the compressor?
3. For what purpose is the oil from the sump picked up by the oil rings?
4. For what purpose is the oil pushed along the shaft?
7.
To drive drove driven /
To bring brought brought -
To take took taken /
To stand stood stood -
To burn burnt burnt -
To hold held held - /
To show showed shown -
To cast cast cast ()
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To tell told told -
To speak spoke spoken - /
To run ran run
To put put put - /
To make made made - -
To do did done
To go went gone -
To forget forgot forgotten -
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To get got got
8. , . .
. , . .
1. . What is the function of link belts?
2. .What is the function of front spirals?
3. , . What is the function of rear spirals?
4. . What is the function of the oil ring?
5. . What is the function of oil pumps?
6. . What is the function of magnets?
10. 2. , . .
.
I. .
II 3 damage, to libricate, viscosity.
1. On no account should lubrication of working parts be stopped because it would cause serious damage of compressor.
2. Compressors are lubricated by oil pumps.
3. Viscosity is one of the most important physical properties of mineral oil used for a compressor.
III. : under, from, on, in, by, with, inside.
1. The direction of rotation must be altered under no circumstances.
2. These compessors are libricated by splash.
3. The oil rings pick up the oil from the sump.
4. Bearings are pressed into housings.
5. Bearings are lined with white babbit.
6. Ordinary engine oil must be used in the crankcase on no account.
7. A magnet is fitted inside the strainer.
8. A magnet assists in collecting fragments.
9. The lubricating system is shown in Fig.2.
IV. should, . .
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1. .
2. .
3. .
4. .
5. .
:
As an unsuitable oil may cause trouble, a pure mineral oil of the following specification should be used.
Under no circumstances should the direction of rotation be altered as this would stop lubrication of the working parts and quickly cause serious damage.
V. . . :
Specific gravity , flash point , pour point , viscosity - , density , sulphur content , mechanical admixtures .
VI. .
1. The function of the compessor to compress vapuor from evaporator.
2. Yes, the compressor delivers agent vapour to the condenser.
3. There are displacement, screw, rotary, centrifugal compressors.
4. The compressor may be a twin cylinder, a triple cylinder, a multi cylinder.
5. The suction strainer is located in the square box located on the rear end of the cylinder block.
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6. The magnet is fitted inside the strainer basket to collect any foreign metal fragments..
7. Delivery and suction valves are mounted on the plate.
8. Bottom ends of the connecting rods are lined with white metal.
9. The crankshaft is carried on two main bearings.
10. The thrust washes are placed at the end of the crankshaft to take end bearings.
11. The compressors are lubricated by oil pumps.
12. Oil rings pick up oil from the sump and deposit it on the top of the crankshaft.
13. Front spirals push oil into the gland box and rear spirals push it backward into the space behind the shaft.
14. Passageways in the shaft are shown dotted in Fig.2.
15. No, only a pure mineral oil should be used in the compessor crankcase.
16. Specific gravity, flash point, puor point, density, sulphur content, mechanical admixtures.
17. The compressor may be driven by an electric motor.
18. A flexible coupling is used to connect the motor to the compressor.
19. The normal rotation is clockwise looking on the flywheel end.
20. Yes, the change in direction of rotation cause serious damage.
21. Yes, the change of the direction of rotation would stop lubrication of the working parts.
VII. . .2. .
1. . 2. . 3. . 4. . 5. .
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3.
.
. , , .
.
, .
, , . . . . . , , . , , , , , . , , . .
, , .
.
1. .
2. :
High pressure gas , liquid refrigerant , expansion valve - () , water cooled condenser , shell and-tube type condenser , outside of the tubes , are expanded into tube plates , are fitted with , to prevent oscillations , due to vibration , safety valves , are provided on the condenser , inside the tubes , water heads , plates are fitted , corrosive action , consumable items , to keep in stock , danger of freezing , refrigerating machinery .
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3. , .
4. , :
1. , ?
2. , ?
3. , ?
4. , ?
5. , ?
6. , ?
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5. .
1. , .
2. , .
3. , .
4. , .
5. 3 . .
.
I. .
II. .
The hot, high pressure gas from the compressor is cooled in the condenser.
The condenser is cooled by water.
The tubes are expanded into the tube plates or soft soldered.
Large condensers are fitted with one or more support plates.
Safety valves are provided on the large condensers.
Anti corrosion plates are fitted in the water heads.
These plates are made of some material.
III. .
1. Shell and tube type or water condensers are widely used in maritime practice.
2. The condenser can be cooled by water or air.
3. Condenser tubes are expanded into the tube plates.
4. Safety valves are provided on large condensers. The refrigerant condenses on the outside of the tubes.
5. Support plates prevent oscillations of the tubes during vibration of the ship.
IV. .
The cooling water circulates inside the tubes fitted inside the condenser.
Liquid refrigerant collects in the bottom of the condenser. There is an outlet for freon liquid in the bottom of the condenser.
Water heads are located at the ends of the condenser. Tubes are expended into tube plates at the ends.
Vibrations in the ship may cause damages of pipes during the rough sea (storm).
Outside of the tubes is covered with the refrigerant. Outside of the tubes should be expected from time to time.
V. .
Cools is cooled * -
Condenses is condensed * -
Collects is collected *
Covers is covered * -
To provide are provided * -
To protect are protected * -
To maintain are maintained *
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To fit are fitted * -
VI. . . .
1. I know shell tube condensers and water type condensers.
2. The condenser can be cooled by water or, in the small size, air.
3. Liquid refrigerant collects in the bottom of the condenser whence it flows to the receiver and the expansion valve
4. Tubes and tube plates are made of special brass or plastic covered steel.
5. The refrigerant condenses on the outside of the tubes.
6. Support plates should be fitted to prevent oscillations of the tubes.
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7. The cooling water circulates inside the tubes beginning from water heads at the ends of the condenser then passing it through the desired number of tubes at a time. then it leaves the condenser through the water outlet and enters again through the water inlet.
8. Anti corrosion plates are fitted in the water heads to lessen the corrosive action of sea water on the material of which the condenser is made.
9. The inside of covers should be protected by painting.
10. The water in tubes must be drained to prevent corrosion if the refrigerating machinery is not in use.
VII. , , .
. , , . () , . , . ( ) .
VIII. .3 .
1. .
2. .
3. .
4. .
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4.
.
. . , .
7 12, .
30 + 10 2 8 .
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1. .
2. 12.
3. 7000 / .
: , 3 5 .
4. 30 _ 10 .
5. , , 2 8 .
6. 12 /2.
7. 3.3 /2.
8. 3.0 .
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12 , , () . () .
, , . , , , . , , , , ; .
.
1. .
2. .
Expansion valve ( ), product cooling , deep freezing unit , low pressure drop , heat transfer , constant degree of superheating , vaporization of the liquid , external equalized thermovalve - , operating conditions , main technical data , rated output - , range of vapourization temperatures , actuator piping , capillary pipe , regulating mechanism , working state , to turn in anticlockwise direction , adjusting spring , to increase the superheating , valve mechanism .
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3. .
4. :
1. Why is the adjusting spring compressed?
2. Why is superheating increased by 4 degrees C?
3. Why is the spring fastened to the inside of the valve body?
4. Why is the length of the capillary pipe sometimes lessened?
5. Why is full vapourization of the liquid ensured?
5. , .
Long length *
High height * -
Deep depth * -
Wide width *
6. .
1. . What is the internal equalized valve used for?
2. () . What is the actuator used for?
3. () . What is the thermostatic valve used for?
4. . What is proper super heating used for?
5. . What is this thermovalve used for?
7. :
low lower the lowest
high higher the highest
large larger the largest
simple simplier the simpliest
easy easier the easiest
good better the best
bad - worse the worst
effective more effective the most effective
complicated more complicated the most complicated
important more important the most important
different more different the most different
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7. 4 . .
.
I. .
II. 5 .
1. Rated output is a number of kilogram calirie produced by a machine per hour.
2. The thermovalve is used in dry refrigeration systems and consists of the actuator, the body, and the regulating mechanism.
3. The thermovalve automatically maintains a constant degree of super heating of freon vapours in the evaporator.
4. It is very important to ensure proper operating conditions of the machine.
5. Crankcase is filled with a pure mineral oil. The actuator is filled with freon.
III. , : regulating, range, expansion.
Thermostatic expansion valve, in the range of vaporization temperatures, the working range, a range of temperatures, regulating mechanism, regulating screw.
IV. :
1. The actuator is filled with freon 12.
2. The regulating screw can be turned in anticlockwise derection for increasing the superheating.
3. The spring constitutes the operating mechanism of the of the regulating screw.
4. If necessary, the length of capillary pipe can be extended.
5. The working range of vaporization temperatures is from 30 C to +10 C.
6. The working pressure on the inlet and outlet of the thermovalve varies from 12 kg/cm2 to 3.3 kg/cm2.
7. Refrigerating systems are used for cooling.
V. . ? .
a) 1. What basic units does the thermovalve consist of? : , , , .
2. What does the actuator consist of? , .
3. What does the valve mechanism consist of? , , .
b) 4. How is a degree of superheating of Freon 12 maintained? 12 .
5. How is the temperature on the evaporator outlet maintained? .
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VI. .
1. For product cooling.
2. Internal equilized valves is used with low pressure drop.
3. External equilized valves are used when there are ferrigerant distributors in the system.
4. The thermovalve TPB - 7 is intended for automatical maintaining a constant degree of superheating of Freon 12 vapours in the evaporator.
5. The working medium, the refrigerant in the systen is Freon 12.
6. Yes, the thermovalve maintains the proper operating conditions of the machine.
7. The difference of the refrigerant temperatures of supergeating from 2 degrees C to 8 degrees C on the inlet and outlet of the evaporator.
8. 7? 22 .
9. The rated uotput is ensured when all proper operating conditions of the machine are observed.
10. The superheating is aligned by turning the regulating screw in anticlockwise direction.
11. The length of the actuator piping is 3/0 meters.
12. The actuator is filled with Freon 12.
13. The thermovalve consist of the actuator, the body, the valve, the regulating mechanism.
14. The diagram is enclosed in the head of the thermovalve.
15. Yes, the actuator brings the valve mechanism in a working state.
16. Yes, the body serves as a foundation.
17. The regulating screw can be turned into anticlockwise direction.
18. The superheating is increased by turning the regulating screw in anticlickwise direction.
19. Yes, the spring constitutes the operating mechanism of the thermovalve.
VII. . 4. .
1. .
2. .
3. 7.
4. .
5. : a) , b) , c) , d) .
VIII. . .
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